This invention relates to a hemicapillar plate dialyzer, made of plastic materials, the active plates thereof securing on one side a turbulent flow of the dialyzing solution and on the other side a laminar flow of blood, whereby the supply and removal of both media are guided so as to secure a uniform filling of contact surfaces of the plates without forming static zones.
The dialyzer is the main part of a system called an "artificial kidney" for the treatment of failures of the kidneys in cases where the kidney function fails due to some injury, due to toxic harm, or due to a sudden or chronic inflammation. Without the normal function of the kidney due to poisoning by nitrogenous compounds, or due to the accumulation of potassium or of other body liquids, the patient dies.
In such cases the equilibrium of the internal constitution of the organism of the patient may be restored by hemodialysis by means of a dialyzer of the coil type, the plate type, or of the capillary type, the dialyzer acting as a filter and eliminating from the human body products of nitrogen metabolism and adjusts the volume of body liquids and electrolytes.
A disadvantage of known dialyzers is the substantial screening of the semipermeable diaphragm, which has to be offset by an increase of the overall weight of the dialyzer; further drawbacks reside in the unfavorable hydrodynamics of the flow of blood and of the dialyzing solution. Thus along the blood channels on the diaphragm there may be formed a stagnant slowly flowing limit layer of blood, such layer being thicker the slower the blood flows. This means that molecules of the offending materials have to pass not only through pores of the semipermeable diaphragm, but must overcome also the resistance of the stable layer of liquids on both sides of the diaphragm. The inlet and outlet of blood and of the dialyzing solution does not always insure with known solutions a full utilization of the contact surfaces, and static zones are created, which may cause an agglutination of blood. There are, furthermore, problems with the tightness of the whole system of the dialyzer, where rather high press forces are required in order to secure the tightness of the system; this entails the danger of breaking the relatively fragile diaphragms. The problem of tightness of the whole system results from the fact that the plates are made of materials of equal hardness, with inaccuracies of manufacture. A consequence thereof is that the plates do not mutually adjust in shape even though a high press force is used in the system. The high press force has to be compensated for by a more complex construction of the dialyzer, which results in a higher weight of the dialyzer. For this reason, high demands are made on dialyzers and on their arrangement, namely;
1. The effect of hemodialysis has to be satisfactory, even for small amounts of blood in the dialyzer. PA1 2. The resistance to blood flow has to be as low as possible in order that a blood pump shall not be required. PA1 3. The residue of blood in the dialyzer after treatment of the patient should be so small, that it would not be required to supply the patient with compensatory blood, thereby overcoming the danger of contracting jaundice or hepatitis. PA1 4. The attendant of the artificial kidney should be protected from contact with blood or with the dialyzing solution, also to prevent any transmission of jaundice or hepatitis. PA1 5. The overall weight of the dialyzer should be as small as possible, and its components should be capable of being mass produced in order that it shall be used only once to prevent any danger of cross infection. PA1 6. The passage of blood should be laminar, and the passage of the dialyzing solution should be turbulent, and should be uniform in both the longitudinal and transverse directions in order fully to utilize the contact surfaces without the creation of static zones. PA1 7. The dialyzer has to form a part of a closed system which includes the patient. PA1 8. In order to achieve an effective cleaning of blood the dialyzer has to consist of a selectable number of similar components assembled by a simple manipulation. PA1 9. The diaphragms have to be securely mounted in the system, without undue stress, in order to reduce the danger of breakage. PA1 10. The dialyzer must be perfectly tight and its arrangement should prevent any direct contact of blood with the dialyzing solution.